Digestion of Bacteria by Nais Variabilis (Oligochaeta) as Established by Autoradiography

Abstract

Serratia marcescens grown on different tritiated substrates was fed to Nais variabilis for 40 min, 4 h and 17 h periods. The substrates were glucose, thymidine and glycerol which labeled mainly low MW compounds, DNA and lipids, respectively. The worms incorporated radioactive label into their tissues within 40 min of feeding on the labeled bacteria. Incorporation of label where low MW compounds were labeled could be due to absorption of dissolved bacterial secretions through the gut or body wall. DNA is a macromolecule not secreted by bacteria; consequently the label within this molecule could only accumulate in worm tissue after digestion, absorption and assimilation. No definite pattern of uptake or translocation along the worm was conclusively established, but there was indication that uptake was greatest in the anterior region of the intestine. Bacterial lipids were digested more slowly than the other materials labeled.